SQL最大/最小查询和数据转换(sql max/min query and data transfo

2019-09-22 21:55发布

更新:改一次表明,每票货的时间可能不按顺序始终。

这里是我的输入

create table test
(
    shipment_id int,
    stop_seq tinyint,
    time datetime
)

insert into test values (1,1,'2009-8-10 8:00:00')
insert into test values (1,2,'2009-8-10 9:00:00')
insert into test values (1,3,'2009-8-10 10:00:00')
insert into test values (2,1,'2009-8-10 13:00:00')
insert into test values (2,2,'2009-8-10 14:00:00')
insert into test values (2,3,'2009-8-10 20:00:00')
insert into test values (2,4,'2009-8-10 18:00:00')

我想要的输出低于

shipment_id  start    end
-----------  -----    ---
     1        8:00    10:00
     2        13:00   18:00

我需要从采取的时间min(stop)行对于每个装运和时从max(stop)分别列和放置在开始/结束。 我知道这可以用多个查询,而很容易做到,但我想看看是否一个选择查询可以做到这一点。

谢谢!

Answer 1:

我想,你就可以做到这一点的唯一方法是使用子查询。

SELECT shipment_id
    , (SELECT TOP 1 time 
        FROM test AS [b] 
        WHERE b.shipment_id = a.shipment_id 
        AND b.stop_seq = MIN(a.stop_seq)) AS [start]
    , (SELECT TOP 1 time 
        FROM test AS [b] 
        WHERE b.shipment_id = a.shipment_id 
        AND b.stop_seq = MAX(a.stop_seq)) AS [end]
FROM test AS [a]
GROUP BY shipment_id

你需要使用DATEPART函数砍时间列,让您精确的输出。



Answer 2:

使用公用表表达式(CTE) - 这个工程(至少在我的SQL Server 2008测试系统):

WITH SeqMinMax(SeqID, MinID, MaxID) AS
(
    SELECT Shipment_ID, MIN(stop_seq), MAX(stop_seq)
    FROM test
    GROUP BY Shipment_ID
)
SELECT 
    SeqID 'Shipment_ID',
    (SELECT TIME FROM test 
       WHERE shipment_id = smm.seqid AND stop_seq = smm.minid) 'Start',
    (SELECT TIME FROM test 
       WHERE shipment_id = smm.seqid AND stop_seq = smm.maxid) 'End'
FROM seqminmax smm

SeqMinMax CTE为每个“shipment_id”选择最小值和最大值“stop_seq”值,并且查询的其余部分然后生成这些值从表中“测试”检索相关联的时间。

CTE的支持SQL Server 2005的(并且是SQL:2003标准的特点 - 没有微软的“发明”,真的)。



Answer 3:

我是正确的,你要在第一时间,而不是“分”的时间思考,而一次的序列,而不是“最大”时间?



Answer 4:

SELECT C.shipment_id, C.start, B2.time AS stop FROM
(    
   SELECT A.shipment_id, B1.time AS start, A.max_stop_seq FROM
   (
      SELECT shipment_id, MIN(stop_seq) as min_stop_seq, MAX(stop_seq) as max_stop_seq 
      FROM test
      GROUP BY shipment_id
   ) AS A

   INNER JOIN 

   (
      SELECT shipment_id, stop_seq, time FROM test
   ) AS B1

   ON A.shipment_id = B1.shipment_id AND A.min_stop_seq = B1.stop_seq
) AS C

INNER JOIN

(
   SELECT shipment_id, stop_seq, time FROM test
) AS B2

ON C.shipment_id = B2.shipment_id AND C.max_stop_seq = B2.stop_seq


Answer 5:

select t1.shipment_id, t1.time start, t2.time [end]
from (
    select shipment_id, min(stop_seq) min, max(stop_seq) max
    from test
    group by shipment_id
) a
inner join test t1 on a.shipment_id = t1.shipment_id and a.min = t1.stop_seq 
inner join test t2 on a.shipment_id = t2.shipment_id and a.max = t2.stop_seq 


Answer 6:

我建议你把ROW_NUMBER和枢纽的优势。 这可能会显得凌乱,但我认为这将表现良好,而且它更适用于各种假设。 例如,它不认为最新的日期时间值对应于给定的货物最大stop_seq值。

with test_ranked(shipment_id,stop_seq,time,rankup,rankdown) as (
  select
    shipment_id, stop_seq, time,
    row_number() over (
      partition by shipment_id
      order by stop_seq
    ),
    row_number() over (
      partition by shipment_id
      order by stop_seq desc
    )
  from test
), test_extreme_times(shipment_id,tag,time) as (
  select
    shipment_id, 'start', time
  from test_ranked where rankup = 1
  union all
  select
    shipment_id, 'end', time
  from test_ranked where rankdown = 1
)
  select
    shipment_id, [start], [end]
  from test_extreme_times
  pivot (max(time) for tag in ([start],[end])) P
  order by shipment_id;
  go

是不是真的需要枢轴,但它很方便。 但是,请注意,PIVOT表达式中的MAX没有做任何有用的东西。 还有每个标签只有一个[时间]值,那么MIN会很好的工作。 语法要求在这个位置上的聚合函数。

附录:这里的,如果你有一台出货量可能比使用MIN和MAX更有效CptSkippy的解决方案的适应性:

SELECT shipment_id
    , (SELECT TOP 1 time 
        FROM test AS [b] 
        WHERE b.shipment_id = a.shipment_id 
        ORDER BY stop_seq ASC) AS [start]
    , (SELECT TOP 1 time 
        FROM test AS [b] 
        WHERE b.shipment_id = a.shipment_id 
        ORDER BY stop_seq DESC) AS [end]
FROM shipments_table AS [a];


文章来源: sql max/min query and data transformation